Swordfish Technique
Swordfish is the bigger sibling of X-Wing. It works with three rows and three columns instead of two, making it more powerful but also more complex.
Expert
What is Swordfish?
Swordfish is an extension of the X-Wing technique to three dimensions. When a candidate appears in at most three cells per row in three rows, and all these cells are in the same three columns, you can make eliminations.
How to Identify a Swordfish
- Find three rows where a candidate appears in at most 2-3 cells
- Check if all these cells fall in the same three columns
- Eliminate the candidate from all other cells in those three columns
Example
If the number 5 can only appear in columns 1, 4, and 7 in rows 2, 5, and 8, this forms a Swordfish. You can then remove 5 as a candidate from all other cells in columns 1, 4, and 7.
Pro Tips
- Master X-Wing before attempting Swordfish
- Swordfish occurs less frequently but is essential for the hardest puzzles